android 蓝牙4.0多通道

很久没记录东西了，前段时间研究了一哈android4.0控制多个外设的情况，注意，需要使用android版本4.3以上，蓝牙4.0及以上。

我这里使用的控制蓝牙灯泡，使用android4.3的手机，手机上的蓝牙是4.0.

记得在manifest文件中加入权限：

 <uses-permission android:name="android.permission.BLUETOOTH" />
 <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />

先拿到BluetoothManager和BluetoothAdapter的对象。

        // 初始化 Bluetooth adapter, 通过蓝牙管理器得到一个参考蓝牙适配器(API必须在以上android4.3或以上和版本)
        final BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
        mBluetoothAdapter = bluetoothManager.getAdapter();

        // 检查设备上是否支持蓝牙
        if (mBluetoothAdapter == null) {
            Toast.makeText(this, R.string.error_bluetooth_not_supported,Toast.LENGTH_SHORT).show();
            finish();
            return;
        }

看下是否开启了蓝牙，如果没有开启，跳转到设置去开启蓝牙。

// 为了确保设备上蓝牙能使用, 如果当前蓝牙设备没启用,弹出对话框向用户要求授予权限来启用
        if (!mBluetoothAdapter.isEnabled()) {
            if (!mBluetoothAdapter.isEnabled()) {
                Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
                startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
            }
        }

调用startScan方法开始扫描，stopScan方法停止扫描，扫描到的设备都在回调函数里。

private void scanLeDevice(final boolean enable) {
        if (enable) {
            // Stops scanning after a pre-defined scan period.
            mHandler.postDelayed(new Runnable() {
                @Override
                public void run() {
                    mScanning = false;
                    mBluetoothAdapter.stopLeScan(mLeScanCallback);
                    invalidateOptionsMenu();
                }
            }, SCAN_PERIOD);

            mScanning = true;
            mBluetoothAdapter.startLeScan(mLeScanCallback);
        } else {
            mScanning = false;
            mBluetoothAdapter.stopLeScan(mLeScanCallback);
        }
        invalidateOptionsMenu();
    }

// Device scan callback.
    private BluetoothAdapter.LeScanCallback mLeScanCallback = new BluetoothAdapter.LeScanCallback() {

        @Override
        public void onLeScan(final BluetoothDevice device, int rssi,
                byte[] scanRecord) {
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    mLeDeviceListAdapter.addDevice(device);
//                    mLeDeviceListAdapter.notifyDataSetChanged();
                }
            });
        }
    };

扫描后的BluetoothDevice加入到列表中，这时列表中就会有设备，通过getName可以获取设备的蓝牙名字，getAddress获取设备的蓝牙地址。

列表出来了之后，点击某个设备进行连接。

注意这里的连接跟2.0的蓝牙的连接不一样，通过设备的connectGatt方法进行连接，连接完成后会获得一个BluetoothGatt的对象，这个对象中有连接的一些重要信息，切记要保存好。

public boolean connect(final String address) {
        if (mBluetoothAdapter == null || address == null) {
            Log.w(TAG, "BluetoothAdapter not initialized or unspecified address.");
            return false;
        }

        if (mBluetoothDeviceAddress != null
                && address.equals(mBluetoothDeviceAddress)
                && mBluetoothGatt != null) {
            Log.d(TAG,
                    "Trying to use an existing mBluetoothGatt for connection.");
            if (mBluetoothGatt.connect()) {
                return true;
            } else {
                return false;
            }
        }

        final BluetoothDevice device = mBluetoothAdapter
                .getRemoteDevice(address);
        if (device == null) {
            Log.w(TAG, "Device not found.  Unable to connect.");
            return false;
        }
        // We want to directly connect to the device, so we are setting the
        // autoConnect
        // parameter to false.
        mBluetoothGatt = device.connectGatt(this, true, mGattCallback);
        Log.d(TAG, "Trying to create a new connection.");
        mBluetoothDeviceAddress = address;
        bluetoothGatts.add(mBluetoothGatt);
        return true;
    }

连接时有一个回调函数mGattCallback，这个函数中有很多设备的相关信息，比如设备的状态啊，设备中的通道哈，一些服务啊之类的。

    // Implements callback methods for GATT events that the app cares about. For
    // example,
    // connection change and services discovered.
    private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {

        @Override
        public void onConnectionStateChange(BluetoothGatt gatt, int status,
                int newState) {
            System.out.println("onConnectionStateChange");
            String intentAction;
            if (status == BluetoothProfile.STATE_DISCONNECTED
                    && newState == BluetoothProfile.STATE_CONNECTED) {
                intentAction = ACTION_GATT_CONNECTED;
                Log.i(TAG, "Connected to GATT server.");
                // Attempts to discover services after successful connection.
                Log.i(TAG, "Attempting to start service discovery:"
                        + mBluetoothGatt.discoverServices());
                Log.e("shang", "连接成功");
                mHandler.sendEmptyMessage(MESSAGE_START_SUCCESS);
            } else if (status == BluetoothProfile.STATE_DISCONNECTED
                    && newState == BluetoothProfile.STATE_DISCONNECTED) {
                intentAction = ACTION_GATT_DISCONNECTED;
                setConnStatus(false);
                Log.e("shang", "连接失败");
                Log.i(TAG, "Disconnected from GATT server.");
                mHandler.sendEmptyMessage(STATE_CONNECTFAILED);
            }
        }

        @Override
        public void onServicesDiscovered(BluetoothGatt gatt, int status) {
            System.out.println("onServicesDiscovered-----");
            if (status == BluetoothGatt.GATT_SUCCESS) {
                broadcastUpdate(ACTION_GATT_SERVICES_DISCOVERED);
                displayGattServices(getSupportedGattServices());
                mHandler.sendEmptyMessage(MESSAGE_BLUETOOTH_INIT);
            } else {
                Log.w(TAG, "onServicesDiscovered received: " + status);
            }
        }

        @Override
        public void onCharacteristicRead(BluetoothGatt gatt,
                BluetoothGattCharacteristic characteristic, int status) {
            System.out.println("onCharacteristicRead");
            if (status == BluetoothGatt.GATT_SUCCESS) {
                broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
            }
        }

        @Override
        public void onDescriptorWrite(BluetoothGatt gatt,
                BluetoothGattDescriptor descriptor, int status) {

            System.out.println("onDescriptorWriteonDescriptorWrite = " + status
                    + ", descriptor =" + descriptor.getUuid().toString());
        }

        @Override
        public void onCharacteristicChanged(BluetoothGatt gatt,
                BluetoothGattCharacteristic characteristic) {
            broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
            if (characteristic.getValue() != null) {

                System.out.println(characteristic.getStringValue(0));
            }
            System.out.println("--------onCharacteristicChanged-----");
        }

        @Override
        public void onReadRemoteRssi(BluetoothGatt gatt, int rssi, int status) {

        }

        public void onCharacteristicWrite(BluetoothGatt gatt,
                BluetoothGattCharacteristic characteristic, int status) {
            System.out.println("--------write success----- status:" + status);
        };
    };

连接时会走这个方法onConnectionStateChange，传过来的新状态是连接状态，这时在这个方法中调用一下这句：mBluetoothGatt.discoverServices()，

mBluetoothGatt是连接完成时的对象，还记得吧，调用这句后，会走回调函数的onServicesDiscovered方法。在这个方法中去获取设备的一些服务，蓝牙通道，然后通过这些通道去发送数据给外设。

查看该外设中支持的一些服务通道：

public List<BluetoothGattService> getSupportedGattServices() {
        if (mBluetoothGatt == null)
            return null;

        return mBluetoothGatt.getServices();
    }

// Demonstrates how to iterate through the supported GATT
    // Services/Characteristics.
    // In this sample, we populate the data structure that is bound to the
    // ExpandableListView
    // on the UI.
    private void displayGattServices(List<BluetoothGattService> gattServices) {
        if (gattServices == null)
            return;
        String uuid = null;
        ArrayList<HashMap<String, String>> gattServiceData = new ArrayList<HashMap<String, String>>();
        ArrayList<ArrayList<HashMap<String, String>>> gattCharacteristicData = new ArrayList<ArrayList<HashMap<String, String>>>();
        mGattCharacteristics = new ArrayList<ArrayList<BluetoothGattCharacteristic>>();

        // Loops through available GATT Services.
        for (BluetoothGattService gattService : gattServices) {
            HashMap<String, String> currentServiceData = new HashMap<String, String>();
            uuid = gattService.getUuid().toString();
            gattServiceData.add(currentServiceData);

            ArrayList<HashMap<String, String>> gattCharacteristicGroupData = new ArrayList<HashMap<String, String>>();
            List<BluetoothGattCharacteristic> gattCharacteristics = gattService
                    .getCharacteristics();
            ArrayList<BluetoothGattCharacteristic> charas = new ArrayList<BluetoothGattCharacteristic>();

            // Loops through available Characteristics.
            for (BluetoothGattCharacteristic gattCharacteristic : gattCharacteristics) {
                charas.add(gattCharacteristic);
                HashMap<String, String> currentCharaData = new HashMap<String, String>();
                uuid = gattCharacteristic.getUuid().toString();
                gattCharacteristicGroupData.add(currentCharaData);
            }
            mGattCharacteristics.add(charas);
            gattCharacteristicData.add(gattCharacteristicGroupData);
        }
        bluetoothGattChacteristics.add(mGattCharacteristics);
    }

然后就可以通过Gatt这个对像，就是蓝牙连接完成后获取到的对象，通过这个对象设置好指定的通道向设备中写入和读取数据。

写数据：

public void wirteCharacteristic(BluetoothGattCharacteristic characteristic) {

        if (mBluetoothAdapter == null || mBluetoothGatt == null) {
            Log.w(TAG, "BluetoothAdapter not initialized");
            return;
        }

        mBluetoothGatt.writeCharacteristic(characteristic);
    }

读数据：

/**
     * Request a read on a given {@code BluetoothGattCharacteristic}. The read
     * result is reported asynchronously through the
     * {@code BluetoothGattCallback#onCharacteristicRead(android.bluetooth.BluetoothGatt, android.bluetooth.BluetoothGattCharacteristic, int)}
     * callback.
     *
     * @param characteristic
     *            The characteristic to read from.
     */
    public void readCharacteristic(BluetoothGattCharacteristic characteristic) {
        if (mBluetoothAdapter == null || mBluetoothGatt == null) {
            Log.w(TAG, "BluetoothAdapter not initialized");
            return;
        }
        mBluetoothGatt.readCharacteristic(characteristic);
    }

注意：BluetoothGattCharacteristic这个是指定的通道，蓝牙服务：

BluetoothGattCharacteristic characteristic = null;
characteristic = mGattCharacteristics.get(4).get(4);

这两个数字就是从指定的服务中找到你要发送数据的那个服务。

　 最后，如果要进行多个连接，每次连接完成后可以将BluetoothGatt的对象放到一个list里面，获取到的服务也放到一个List里面，然后发送数据的时候调用不同的Gatt发送不同的通道数据即可。

关于蓝牙4.0的BluetoothLeGatt连接，android Samples有一个例子，发上来吧，需要的朋友可以下载看看。

BluetoothLeGatt